Music and Lyrics
My husband was born with music in his bones; he can pick up an instrument he has never played and pick out a recognizable tune within half an hour; he is an instrumentalist par excellence (the choir only wishes he could pour out his beautiful baritone/bass voice and play the flute simultaneously). And when you see the flute-man jammin', you know he's in his element.
For me, on the other hand, the words and lyrics usually make themselves known before the music; the tune shapes itself from the meanings. Songs come through and find their own way; and sometimes they get away on me if I'm not quick enough to catch them.